The Tempo Adjusted TFR(TFR’) is proposed because of the disadvantages of the Total Fertility Rate in representing the lifetime fertility level.However,is the TFR’ reasonable and accurate? This paper discusses the assumptions,data requirements and calculating method of TFR’.Examinations and tests of the TFR’ are conducted using Chinese data.The paper concludes that the assumptions of this method are problematic,this index is sensitive to the change of the mean age at childbearing,and serious error in the measurement could occur.The issue of the impact of average childbearing age on total fertility rate needs further exploration and research.